The subject matter of the present disclosure is directed to acquiring specific channel information from certain communication systems. The subject matter disclosed allows this information to be gained independently without coordination or cooperation from the mobile communication system.
There are many applications for this method and associated apparatus, for brevity and clarity, the method is described in relation to a communications network, particularly a wireless mobile telephone communication system. Wireless communication systems for mobile telephones have been extensively described in public references FIG. 1 is an illustration of a typical wireless communication system 100. The system has a series of base stations or base station transceivers (BTS) 120a-c controlled by a base station controller (BSC) 110. The BTS 120 communicates over one or more allocated channels with a mobile appliance 150, mobile phone or other type of mobile device such as a computer.
Referring to the FIG. 1, in the case of typical wireless communication networks, the BTS 120 and BSC 110 nodes are not physically co-located, and the information that flows between them is passed on a digital communications facility (communication link) 130a-c such as a T1 or T3 span. Signaling channels as well as voice channels are contained in the T spans. If an auxiliary system (AXS) piggybacked to the system is probing or monitoring the signaling channels to acquire channel assignment information on the T spans, the monitors of the auxiliary system must know where on the T spans the signaling channel resides in the mix of voice or other data channels. For example, in the case of a T1, there are 24 channels, designated Digital Signaling level “0” (DSO)s, that could contain the signaling information. (Digital Signaling level 0 is the worldwide standard speed for digitizing one voice conversation using pulse code modulation (PCM) and sampling the voice 8,000 times a second and encoding the result in an 8-bit code)
One such system as shown in FIG. 2, places Auxiliary Receivers (AXR) 160 at base station sites, an Auxiliary Control System (ACS) 170 at the mobile switch site (MSC) 140, and an Abis Monitoring Unit (AMU) 180 at the base station controller on the communication link 130 between the BTS 120 and the BSC 110.
In one mode of operation of the wireless system, the Radio Frequency (RF) transmission from a mobile of interest 150 (the mobile in which there is an interest in obtaining its transmission signal) is on a specifically assigned channel. A channel in the context of this disclosure can refer to an RF frequency, time slot, message assignment, hopping sequence, encryption key, etc. Knowing the channel assignment for the mobile of interest allows the AXR 160 units to receive the RF energy uniquely from this mobile appliance for use in quality measurements, detection, interception and exploitation of the communication or other auxiliary use of the mobile's transmitted signal. In some instances, the channel assignment information is provided cooperatively to the auxiliary system (AXS) 190 from the host wireless system 100 or network.
In other cases, the channel assignment information must be learned by monitoring or probing certain interfaces in the mobile telephone system 100, such as for detection intercepting and exploiting the communication where cooperation is not expected or in the case where the wireless communication system 100 is overburdened or not equipped to provide such information.
These interfaces where channel assignment information resides are generally called signaling channels. In FIG. 2, the AMU 180 is monitoring the signaling channels between the BTS 120 and the BSC 110 to learn the channel assignments for the mobile of interest 150.
One method to provide this information would be for an AMU 180 to be configured with a table that assigned channels in T spans to signaling channels from specific BTS sites. However, this method becomes ineffective if the signaling channel assignment to a T span channel is dynamic. With the advent of smart antennas and dynamic networks, this is the case for many installations of mobile wireless communication systems.
In the alternative, the channel assignment information must be learned by monitoring or probing certain interfaces in the mobile wireless system to which the subject matter of this disclosure is generally drawn. These interfaces where channel assignment information resides are generally called signaling channels.
Therefore in order to obviate the deficiencies of the prior art, it is an object of the present disclosure to provide a novel method for acquiring channel assignment information by monitoring the communication link 130 between a BSC 110 and a BTS 120.
It is also an object of the present disclosure to present in a communication system a method to acquire signaling information (channel assignment or traffic information) from the communication link with a link tap. The method including monitoring each channel of the communication link for protocol messages and identifying a set of channels with valid protocol messages and, monitoring the set of channels to determine the transceivers served by the set of channels and associating the transceivers with respective channels from the set of channels. The novel method also includes monitoring messages of each of the channels associated with the transceivers to determine broadcast channels assigned to the transceiver. The method further includes mapping the broadcast channels to a network device, and monitoring the broadcast channels with a receiver to determine a parameter value for the broadcast channel.
It is still an object of the present disclosure to present in a communication network having a base transceiver station and a base station controller operably connected by a communication link with a plurality of channels, a novel method for obtaining traffic information independently without cooperation from the communication system. The method includes dynamically monitoring the communication link for signaling channels with a link tap and mapping channel connections with information, such as channel assignment, obtained from the signaling channels.
It is another object of the present disclosure to present a novel method of dynamically acquiring channel assignments by monitoring signaling channels between network entities connected by a communication link. The method including determining channel data rate; selecting channels in the communication link used for Abis signaling and forming a set of selected channels; monitoring the set of selected channels to detect a known subset of network entities and associating the set of selected channels with the subset of network entities. The novel method also includes monitoring the associated channels for each network entity for broadcast channel values associated with each network entity.
These objects and other advantages of the disclosed subject matter will be readily apparent to one skilled in the art to which the disclosure pertains from a perusal or the claims, the appended drawings, and the following detailed description of the preferred embodiments.